Constraints on the density distribution of type Ia supernovae ejecta inferred from late-time light-curve flattening

Abstract

The finite time, ${\tau }_{\mathrm{dep}}$, over which positrons from ${\beta }^{+}$ decays of ${}^{56}$Co deposit energy in type Ia supernovae ejecta lead, in case the positrons are trapped, to a slower decay of the bolometric luminosity compared to an exponential decline. Significant light-curve flattening is obtained when the ejecta density drops below the value for which ${\tau }_{\mathrm{dep}}$ equals the ${}^{56}$Co life-time. We provide a simple method to accurately describe this "delayed deposition" effect, which is straightforward to use for analysis of observed light curves. We find that the ejecta heating is dominated by delayed deposition typically from 600 to 1200~day, and only later by longer lived isotopes ${}^{57}$Co and ${}^{55}$Fe decay (assuming solar abundance). For the relatively narrow ${}^{56}$Ni velocity distributions of commonly studied explosion models, the modification of the light curve depends mainly on the ${}^{56}$Ni mass-weighted average density, $⟨\rho ⟩t^3$. Accurate late-time bolometric light curves, which may be obtained with JWST far-infrared (far-IR) measurements, will thus enable to discriminate between explosion models by determining $⟨\rho ⟩t^3$ (and the ${}^{57}$Co and ${}^{55}$Fe abundances). The flattening of light curves inferred from recent observations, which is uncertain due to the lack of far-IR data, is readily explained by delayed deposition in models with $⟨\rho ⟩t^3\approx 0.2M_{\odot }(10^4\text{km}{\text{s}}^{-1}{)}^{-3}$, and does not imply supersolar ${}^{57}$Co and ${}^{55}$Fe abundances.

arXiv comment9 pages, 5 figures. Minor revisions following referee's report

References in corpus (35)

• Core-Collapse Supernovae from 9 to 120 Solar Masses Based on Neutrino-powered Explosions
• Observational clues to the progenitors of Type-Ia supernovae
• Radiation hydrodynamics of SN 1987A: I. Global analysis of the light curve for the first 4 months
• Head-on collisions of white dwarfs in triple systems could explain type Ia supernova
• Sub-Chandrasekhar-mass white dwarf detonations revisited
• Spectrophotometric time series of SN 2011fe from the Nearby Supernova Factory
• Observational Predictions for Sub-Chandrasekhar Mass Explosions: Further Evidence for Multiple Progenitor Systems for Type Ia Supernovae
• Constraints on the ejecta of the GW170817 neutron-star merger from its electromagnetic emission
• Gamma-Ray Transfer and Energy Deposition in Supernovae
• Analysis of Late--time Light Curves of Type IIb, Ib and Ic Supernovae
• Positron Escape from Type Ia Supernovae
• Constraints on the explosion mechanism and progenitors of type Ia supernovae
• Inferring supernova IIb/Ib/Ic ejecta properties from light curves and spectra: Correlations from radiative-transfer models
• The late-time light curve of the Type Ia supernova 2000cx
• Late Light Curves of Type Ia Supernovae
• Late-time supernova light curves: The effect of internal conversion and Auger electrons
• Reconciling the infrared catastrophe and observations of SN 2011fe
• Late-Time Photometry of Type Ia Supernova SN 2012cg Reveals the Radioactive Decay of ${}^{57}$Co
• Type Ia supernovae have two physical width-luminosity relations and they favor sub-Chandrasekhar and direct collision models. I. Bolometric
• Whimper of a Bang: Documenting the Final Days of the Nearby Type Ia Supernova 2011fe
• The late-time light curve of the type Ia supernova SN 2011fe
• Late Light Curves of Normal Type Ia Supernovae
• Bolometric light curves of supernovae and post-explosion magnetic fields
• Optical and near infrared observations of SN 1998bu
• Late time kilonova light curves and implications to GW 170817
• Type Ib/Ic supernovae: effect of nickel mixing on the early-time color evolution and implications for the progenitors
• Extremely late photometry of SN~2011fe
• Late-time Flattening of Type Ia Supernova Light Curves: Constraints From SN 2014J in M82
• Observations of SN 2015F suggest a correlation between the intrinsic luminosity of Type Ia supernovae and the shape of their light curves >900 days after explosion
• A year-long plateau in the late-time near-infrared light curves of Type Ia supernovae
• Late-Time Observations of ASASSN-14lp Strengthen the Case for a Correlation between the Peak Luminosity of Type Ia Supernovae and the Shape of their Late-Time Light Curves
• Observations of Type Ia Supernova 2014J for Nearly 900 Days and Constraints on Its Progenitor System
• Late-Time Observations of Type Ia Supernova SN 2014J with the Hubble Space Telescope Wide Field Camera 3
• Did SN 1989B Exhibit a Light Echo?
• Late Light Curves of Normally-Luminous Type Ia Supernovae

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